Resonant Brillouin scattering in semiconductors

Abstract

The exciton-polariton resonance in Brillouin scattering makes this type of light scattering an ideal probe for (i) the investigation of polariton dispersion curves and (ii) the exciton-phonon interaction. The peculiar kinematics of resonant Brillouin scattering allow the practice of k-space spectroscopy near k=0 and the precise determination of exciton parameters. The light scattering intensities give insight into the microscopic nature of the coupling of the phonons to the electronic states which determine the optical properties of semiconductors. Experimental Brillouin spectra in the vicinity of the lowest excitons in direct gap III–V and II–VI semiconductors are analyzed in the context of the polariton scattering concept introduced by Hopfield. The connection between multiple (elastic and inelastic) scattering of polaritons, their fluorescence and the phenomenon of exciton absorption is discussed.

At the lattice temperatures discussed here one has Nq/Nq+1≤1.2 in equilibrium. Deviations from phonon equilibrium are improbable under the given excitation power densities.Google Scholar

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Ref. 20 contains a numerical error in the computation of vg. The correct value of vg at 0.5 meV below ET is 4.7×107 cm/s. This leads to a theoretical understimate (∼factor 0.2) of the actually measured efficiency.Google Scholar